The present invention relates to an information playback apparatus capable of performing random access playback to start playback from an arbitrary portion, reverse playback, shuttle playback, etc. when playing back information recorded in an information recording medium, such as a CD (Compact Disc), a DVD (Digital Versatile Disc), and an MD (Mini Disc).
The present application claims priority from Japanese Application No. 2001-316552, the disclosure of which is incorporated herein for all purpose.
As a conventional information playback apparatus for playing back information recorded in an information recording medium, such as a CD, a DVD, and an MD, there is known a type furnished with a random access playback function, a reverse playback function, and a shuttle playback function.
The random access playback function is a function to start playing back information from a position called a cue point, and for example, once the user or the like registers the recording position of desired information by the cue point, he/she can readily find the recording position later by automatic search and start information playback therefrom.
The reverse playback function is a function opposite to a forward playback function generally performed for playing back information. Such reverse playback function is used to play back information in a reverse direction, which is otherwise played back in the forward direction with an elapsing of time. For example, the reverse playback function can offer the same advantage attained when an analog record is played by running the stylus on the analog record in a reverse direction by turning the turntable of an analog record player forcedly in the reverse direction.
Hence, as shown in FIG. 8(a) by way of example, when sound information, such as music, recorded in an information recording medium is played back, the waveform of a playback signal S1 generated and supplied to a loudspeaker or the like in the case of forward playback and the waveform of a playback signal S2 generated in the case of reverse playback are inverted in the time base direction.
The shuttle playback function offers the same advantage attained when the forward playback and the reverse playback are performed alternately.
For example, the user or the like can perform shuttle playback as he/she rotates a rotator DL (called a jog dial provided to the information playback apparatus) back and forth as shown in FIG. 8(b).
To be more specific, the jog dial DL is provided with a sensor SEN for detecting rotational direction and speed of the jog dial DL, and when the user or the like manipulates the jog dial DL back and forth in a clockwise direction Fw and in a counterclockwise direction Bw alternately, a detection signal Sn whose polarity is alternatively reversed as shown in FIG. 8(c) is outputted, whereby forward playback and reverse playback are performed alternately in accordance with a change in the detection signal Sn. Hence, when the jog dial DL is manipulated back and forth quickly while information, such as music, recorded in an information recording medium is being played back, it is possible to play imitation sounds (scratching sounds, etc.) different from the original music.
Incidentally, the conventional information playback apparatus is provided with a buffer memory for storing information (data) of a certain time duration to achieve forward playback and reverse playback.
As shown in FIG. 9 which is an example, in the case of forward playback of information (data) A through S recorded on tracks in an information recording medium, data of a certain time duration (data in the forward direction) is read out at a time in advance by the pickup and stored into a buffer memory BMM, so that an original movie or music is played based on the data stored in the buffer memory BMM.
For example, in the case of forward playback of data M, N, O, and so forth, playback from a time point t1 to a time point t2 is performed under a condition in which the data M, N, and O is stored in the buffer memory BMM. Upon completion of this playback, playback from the time point t2 to a time point t3 is started under a condition in which the data O, P, and Q is stored in the buffer memory BMM. Further, upon completion of this playback, playback from the time point t3 to a time point t4 is started under a condition in which the data Q, R, and S is stored in the buffer memory BMM. By repeating the same processing thereafter, seamless forward playback can be accomplished.
In the case of reverse playback, as shown in FIG. 10 which is an example, data of a certain time duration (data in the reverse direction) is read out at a time in advance by the pickup and stored into the buffer memory BMM, so that the data stored in the buffer memory BMM is played back in the reverse order.
It should be noted, however, that, in the case of an information recording medium, such as a CD and a DVD, there is a limit that data on the tracks always has to be read out along the forward direction, which complicates the readout processing in the case of reverse playback in comparison with the case of forward playback.
For example, in the case of reverse playback of data L, K, J and so forth in a sequence in the reverse direction, the pickup is at first moved to the position of the data J, then the data J, K, L is read out and stored into the buffer memory BMM. Subsequently, reverse playback from a time point t1 to a time point t2 is performed by playing back the data K and L in the reverse direction, and further, the pickup is moved to the position of the data H during this reverse playback to start reading the following data H and I as soon as possible.
Then, reverse playback from the time point t2 to a time point t3 is performed by playing back the data I and J out of the data H, I, and J stored in the buffer memory BMM in the reverse direction, and further, the pickup is moved to the position of the data F during this reverse playback to start reading the following data F and G as soon as possible.
Then, reverse playback from the time point t3 to a time point t4 is performed by playing back (in the reverse direction) the data G and H out of the data F, G, and H stored in the buffer memory BMM, and further, the pickup is moved to the position of the data D during this reverse playback to start reading the following data D and E as soon as possible.
Accordingly, seamless reverse playback can be achieved by repeating the foregoing processing.
However, in the case of shuttle playback for performing forward playback and reverse playback alternately, data for forward playback and data for reverse playback need to be updated and stored alternately into the buffer memory BMM at each transition from forward playback to reverse playback or from reverse playback to forward playback. Hence, the pickup has to be moved promptly to a position of particular data. However, in practice, it is difficult to move the pickup promptly to a position of particular data, and therefore, there may be a case that shuttle playback cannot be achieved in association with the rotations of the jog dial. In particular, there is a problem that shuttle playback cannot be achieved when the jog dial is manipulated back and forth too fast.
Also, in the case of the aforementioned random access playback from an arbitrary portion, when access is made to data positioned at a cue point remote from data currently being played back, it takes a long time to move the pickup to the position of the data to be accessed, and for this reason, a desired quick random access playback cannot be achieved.
Particularly, in the case a user or the like may wish to perform shuttle playback immediately after accessing a desired portion, and at this time, a considerably large load will be applied to the pickup, resulting in a situation which not always but often makes it impossible to achieve playback processing in the manner as the user or the like desires.
The present invention is devised to solve the above conventional problems, and therefore, has an object to provide an information playback apparatus capable of more quickly performing time-consuming playback processing, such as random access playback, reverse playback, and shuttle playback.
In order to achieve the above and other objects, an information playback apparatus of the present invention is an information playback apparatus for playing back information recorded in an information recording medium, including: readout means for reading out the information recorded in the information recording medium; storage means for storing the information read out by the readout means; and information processing means for obtaining the information stored in the storage means and performing information playback processing, wherein: the storage means has a first memory region for storing information of a certain time duration corresponding to a past time and a second memory region for storing information of a certain time duration corresponding to a future time, all with respect to the information obtained by the information processing means; and the readout means reads out the information from the information recording medium to replenish the first memory region and the second memory region with the information.
According to the information playback apparatus of the present invention arranged as above, the readout means reads out information from the information recording medium first, then the storage means stores the information thus read out, and the information processing means performs information playback based on the information stored in the storage means. Herein, the storage means is provided with the first memory region for storing information of a certain time duration corresponding to a past time with respect to the information obtained by the information processing means and the second memory region for storing information of a certain time duration corresponding to a future time with respect to the information obtained by the information processing means, and the readout means replenishes the first and second memory regions with the information of their respective kinds.
Hence, in the case of forward playback, information playback is performed based on the information corresponding to the future time stored in the second memory region in the storage means; in the case of reverse playback, information playback is performed based on the information corresponding to the past time stored in the first memory region in the storage means; and in the case of shuttle playback, information playback is performed based on the information of the respective kinds stored in the first and second memory regions. Further, because the readout means replenishes the first and second memory regions with the information, an unwanted event that information needed for information playback becomes short in the first and second memory regions can be avoided in advance, thereby making it possible to achieve seamless playback, that is, seamless forward playback, reverse playback, and shuttle playback.
The information playback apparatus of the present invention may be arranged in such a manner that it further includes: manipulation means manipulated in a forward direction and in a reverse direction, and that the information processing means obtains the information corresponding to the future time from the second memory region when the manipulation means is manipulated in the forward direction, and obtains the information corresponding to the past time from the first memory region when the manipulation means is manipulated in the reverse direction.
According to the information playback apparatus of the present invention arranged as above, forward playback is performed when the manipulation means is manipulated in the forward direction, reverse playback is performed when the manipulation means is manipulated in the reverse direction, and shuttle playback is performed when the manipulation means is manipulated in the forward direction and in the reverse direction alternately.
The information playback apparatus of the present invention may be arranged in such a manner that the information processing means changes a processing speed of information playback processing for the information obtained from one of the first and second memory regions in response to a manipulation speed when the manipulation means is manipulated in one of the forward direction and the reverse direction.
According to the information playback apparatus of the present invention arranged as above, the processing speed of the information playback processing is changed in response to a manipulation speed of the manipulation means. Consequently, when the manipulation means is manipulated in the forward direction, forward playback is performed depending on the manipulation speed; when the manipulation means is manipulated in the reverse direction, reverse playback is performed depending on the manipulation speed; and when the manipulation means is manipulated in the forward direction and in the reverse direction alternately, shuttle playback depending on a manipulation speed in the forward direction and a manipulation speed in the reverse direction is performed by performing forward playback and reverse playback alternately in response to the manipulation speed in the forward direction and the manipulation speed in the reverse direction, respectively.
Also, an information playback apparatus of the present invention is an information playback apparatus, including: control means for starting playback from arbitrary information recorded in an information recording medium; readout means for reading out information recorded in the information recording medium; first and second storage means for storing the information read out by the readout means; information processing means for obtaining the information stored in one of the first and second storage means and performing information playback processing; and directing means for directing the control means to register the arbitrary information and to start playback from the registered arbitrary information, wherein: the first storage means has a first memory region for storing information of a certain time duration corresponding to a past time and a second memory region for storing information of a certain time duration corresponding to a future time with respect to the information obtained by the information processing means; the second storage means has a first memory region for storing information of a certain time duration corresponding to a past time and a second memory region for storing information of a certain time duration corresponding to a future time with respect to the arbitrary information; once directed by said directing means to register said arbitrary information, said control means controls said readout means to read out the information of the certain time duration corresponding to the past time and the information of the certain time duration corresponding to the future time, which are prior to and subsequent to each other in reference to said arbitrary information, from said information recording medium and store the same into said second storage means, and when directed by said directing means to start the playback from said arbitrary information, said control means controls said information processing means to perform the information playback processing based on the information stored in said second storage means.
According to the information playback apparatus of the present invention arranged as above, it is possible to achieve a so-called random access playback function for accessing arbitrary information recorded in the information recording medium and performing information playback from the accessed information as a starting point.
To be more specific, when directed by the directing means to register arbitrary information, the readout means reads out information prior to and subsequent to each other in reference to the arbitrary information in a time-based relation, that is, information of a certain time duration corresponding to a past time and information of a certain time duration corresponding to a future time, from the information recording medium, and stores the same into the first memory region and the second memory region in the second storage means, respectively. When so-called random access is directed by the directing means later, the information processing means starts random access playback based on the information of the respective kinds stored in the second storage means. By initially starting information playback based on the information stored in the second storage means in this manner in the case of random access playback, it is possible to achieve quick random access playback.
Further, even when so-called random access and reverse playback or shuttle playback are specified substantially at the same time, reverse playback or shuttle playback can be performed based on the information stored in the second storage means, thereby making it possible to achieve quick random access followed by seamless playback.
The information playback apparatus of the present invention may be arranged in such a manner that, while the information processing means is performing the information playback processing based on the information stored in the second storage means, the control means controls the readout means to read out information succeeding the information stored in the second storage means from the information recording medium and store the same into the first storage means, and when storing of the succeeding information into the first storage means is completed, the control means controls the information processing means to switch to the first storage means to obtain the information therefrom.
According to the information playback apparatus of the present invention arranged as above, while the information processing means is performing so-called random access playback based on the information stored in the second storage means, succeeding information is read out from the information recording medium and stored into the first storage means. When storing into the first storage means is completed, information playback processing performed based on the information in the second storage means is switched to information playback processing based on the information stored in the first storage means to continue information playback. Consequently, it is possible to achieve quick random access followed by seamless playback.
The information playback apparatus of the present invention may be arranged in such a manner that the readout means reads out the information from the information recording medium to replenish the first memory region and the second memory region in the first storage means with the information.
According to the information playback apparatus of the present invention arranged as above, in the case of so-called random access playback, the first and second memory regions in the first storage means are replenished with the information after the second storage means is switched to the first storage means. Hence, an unwanted event that information needed for information playback becomes short in the first and second memory regions can be avoided in advance, thereby making it possible to achieve seamless playback.
The information playback apparatus of the present invention may be arranged in such a manner that it further includes manipulation means manipulated in a forward direction and in a reverse direction, and that the information processing means obtains the information corresponding to the future time from one of the second memory region in the first storage means and the second memory region in the second storage means when the manipulation means is manipulated in the forward direction, and obtains the information corresponding to the past time from one of the first memory region in the first storage means and the first memory region in the second storage means when the manipulation means is manipulated in the reverse direction.
According to the information playback apparatus of the present invention arranged as above, forward playback is performed when the manipulation means is manipulated in the forward direction, reverse playback is performed when the manipulation means is manipulated in the reverse direction, and shuttle playback is performed when the manipulation means is manipulated in the forward direction and in the reverse direction alternately. Also, when the manipulation means is manipulated while so-called random access playback is being performed based on the information stored in the second storage means, forward playback, reverse playback, or shuttle playback is performed based on the information stored in the second storage means, and after the information is stored fully into the first storage means during the foregoing playback processing, forward playback, reverse playback, or shuttle playback is continued based on the information stored in the first storage means. Hence, it is possible to achieve quick random access followed by seamless forward playback, reverse playback, or shuttle playback.
The information playback apparatus of the present invention may be arranged in such a manner that the information processing means changes a processing speed of the information playback processing for the information obtained from the first or second memory regions in the first or second storage means in response to a manipulation speed when the manipulation means is manipulated in the forward direction or the reverse direction. According to the information playback apparatus of the present invention arranged as above, forward playback, reverse playback, or shuttle playback is performed depending on a manipulation speed of the manipulation means in the forward direction or in the reverse direction. Also, forward playback, reverse playback, or shuttle playback is performed depending on a manipulation speed of the manipulation means in the forward direction or in the reverse direction, irrespective of whether so-called random access playback is being performed based on the information stored in the second storage means or information playback is being performed based on the information stored in the first storage means.